Digsby shows up just at the right time for me. I like Pidgin fine, but it's not a Windows version of Adium and it feels clunky. While Digsby's Twitter/Facebook/Email integration is nice and I appreciate being able to sync all of my logins so it works on any machine I use (at the price of giving up all my logins to some machine in the sky), some of the subtler features are what sold me (for the 60 seconds more I've been using it than you have). I like being able to only accept IMs from contacts since I get IM spam most of the times I sign into Yahoo. I'm sure Pidgin offers most of the useful features, but well, this is new so it must be better. More useful details at Lifehacker.
I've got to rein in all these windows it's popping up though. It doesn't seem to understand the concept of multiple monitors or when it has focus. I have no idea why I added my Facebook login since all it's going to do is generate a stream of shit aggregated from elsewhere. Facebook feels like a half-assed version of FriendFeed given the way my contacts use it. Oh, there. It just popped up with a status update I don't care about. Hooray for Facebook invading my desktop. Time to live: 2 minutes.